Boston University Discovers Fire

April 9, 2012

Last week, archeologists from Boston University discovered fire, in a manner of speaking. Professors Francesco Berna and Paul Goldberg published research stating they found evidence of man-made fire that, at one million years old, is the oldest one found to date.

Goldberg is a professor of archeology and geoarchaeology and Berna is a research assistant professor of archeology. The two professors were part of a team led by Michael Chazan of the University of Toronto. They were collecting sediment samples in a cave in Wonderwerk, South Africa, when they came across a discovery: the sediments contained traces of burned animal bones and ash.

This meant that early on in our evolutionary history, in our homo erectus period, humans had control of fire.

It is something that was hypothesized, but never certain. Previous evidence indicated that man-made fire was much, much more recent—hundreds of thousands of years more recent. Some evidence put the oldest manmade fires around 800,000 years ago in Gesher Benot Ya`aqov, Israel. There have been other, similarly older sites where evidence of fire was clear, but evidence was not as secure as it was in Wonderwerk.

“The problem with the other sites is that most all of them are open air sites, so it’s very hard to rule out the role of a wildfire burning on top of human remains or carcasses left there,” Berna said. “Our site, Wonderwerk, is a cave, and is a very well protected environment, and so we know that there is no wildfire coming in. It’s related to human activities.”

What made Goldberg and Berna’s study difference was their emphasis on context. Goldberg and Berna work out of the Labratory of MicroStratigraphy in the College of Arts and Sciences. They bring in samples of sediment and scrutinize them right in the lab. What their techniques give them is valuable context. In simplest terms, they carefully collect sediment from the sites, bring it back to the laboratory and look it over.

“The way we work in the lab is we collect a sample of in-tact sediments form the cave, a block the size of a brick, let’s say, a little smaller than a brick. We carefully wrapped it up in toilet paper…and we bring it to the lab and…essentially turn it into a rock, and we slice it once it’s hardened, and mount it on a glass slide,” Goldberg said. “So, once we do that, we can look at the material… under the microscope as if it were a piece of the cave brought back to the laboratory.”

Graphic by Evan Caughey.

That’s how they stumbled upon their discovery. They did not go into the caves looking for evidence of fire (not exactly) and were really just looking to reconstruct the history of the cave using samples. But in terms of history to uncover, moving back the discovery of fire hundreds of thousands of years is fairly substantial, because wrangling control over the destructive and useful fire was a major moment in early human history.

“The control of fire has a biological significance, has an evolutionary significance,” said Berna. “It’s like…humans became humans because they weren’t afraid of fire, they knew how to use fire, and they knew how to cook their food, and so that gave them a huge advantage in terms of energy saving, time saving, and allowed the cultural evolution to rapidly evolve and become what we have now.”

The discovery gives support to one controversial hypothesis about early humans, the cooked food hypothesis of Richard Wrangham. The professor of biological anthropology at Harvard University believed that our ancestor homo erectus was already on a cooked food diet.

“And this is a big, big claim, that very few people believe in terms of archeology,” said Berna. “Because it’s only based on biological evidence and anatomical evidence and not in archeology.”

But now the archeological and geological evidence is present. The cooking of food, Wrangham’s research says, contributed to brain growth and smaller jaws, both important evolutionary differences between homo erectus and homo sapien. The theory remains controversial in multiple scientific communities, but with the contribution of Goldberg and Berna’s discovery, it remains food for thought.

The archeologists also both emphasized the importance of their methods above all else. The team was studying sediments and packaged them for study in the laboratory. Rather than bringing the artifacts to the lab, they brought the whole cave without having to lose any of the contextual information.

“Until people start looking at these sediments as artifacts, if you will, there’s a lot of information that’s being either thrown over the side of the site or just ignored that’s just a gold mine of information,” Goldberg said.